Rising demand for fossil fuels, exasperated by rapidly developing nations, is driving the need for more efficient utilization of limited natural resources in conjunction with the development of alternative energy sources. Many modern advances in long utilized petrochemical practices such as gasification and hydrotreatment are enabling the cost effective utilization of so called unconventional fuels. Hybrid designs such as those discussed in papers “Development of Multifunctional Energy Systems” (Cai et al., Energy, 2010) and “Optimization Framework for the Simultaneous Process Synthesis, Heat and Power Integration of a Thermochemical Hybrid Biomass, Coal, and Natural Gas Facility” (Baliban et al., Computers & Chemical Engineering, 2011) enable the conversion of non-conventional fuels such as coal and natural gas as well as biomass and waste to be converted to direct replacements or additives for petrochemicals conventionally derived from oil. Furthermore, they are capable of utilizing carbon dioxide as a carbon source for conversion to synthetic fuels, oils, and other carbon materials.
These practices do have substantial costs involved however. Capitol costs of equipment as well as further energy costs are incurred depending on the chosen technology and level of carbon dioxide management sought. The reliance on air separation techniques common in high efficiency and especially carbon sequestration applications is one substantial cost. Further notable costs of such systems are hydrogen production methods that typically rely on direct oxidation of fuel inputs which in turn puts a greater load on carbon capture systems. An alternative method of hydrogen production via electrolysis is emissions free but even with onsite electricity production (which typically is not emissions free or highly efficient) represents a steep energy penalty. Even state of the art staged reforming processes coupled to numerous complementary subsystems rely to a large extent on legacy practices of energy production through direct oxidation and may or may not manage the resulting carbon dioxide produced. (US 2012/0073198 A1, U.S. Pat. No. 7,674,443) What is needed is a superstructure that takes advantage of the level of maturity of such legacy processes while integrating advances in alternative energy sources to efficiently deliver process heat. The present invention accomplishes this through the novel integration of hydrogen production with the indirect oxidation by carbochlorination of pyrolysis residues. Through this arrangement, heat is conserved and directed at hydrogen production and carbon dioxide formation is kept to a minimum.
Martynov et al. has shown in “Water and Hydrogen in Heavy Liquid Metal Coolant Technology” (Progress in Nuclear Technology, 2005) that molten lead-bismuth eutectic is an ideal catalyst for steam methane reactions. Combining this advantageous method of hydrogen production with heat amplification techniques allows for a range of viable alternative energy inputs such as direct or indirect heating provided by an advanced high temperature modular nuclear reactor.
Through this unique arrangement of processes, a large number of metallurgical subsystems may be integrated with a variety of synergistic benefits. Those of ordinary skill in the art should recognize the integration of a flash smelter provides for both the management of smelter off gases and an inherent drossing mechanism within the molten metal steam methane reactor. Similarly, steel production through recycling and direct reduction can be incorporated with highly beneficial off gas processing simultaneously complementing the carbochlorination process. A variety of processing methods are available for the extraction of valuable base metals from the feedstock through gaseous and electrochemical methods. In addition to the precious metals inherently captured by the molten metal steam methane reforming, rare earth elements (as well as the various radioactive species typically associated with them) are captured and concentrated by carbochlorination techniques that can be removed through methods already known in the art. (U.S. Pat. Nos. 5,039,336, 5,569,440) Also disclosed is a method of oxidizing the carbon component of carbochlorination residue using metal oxides from integrated processes as well as a novel electrochemical cationic exchange for extraction of residual components utilizing a solid electrolyte. (U.S. Pat. No. 4,664,849) Those of ordinary skill in the art will undoubtedly recognize other varying benefits of the process integration enabled by the present invention.
Finally, by exploiting a staged reforming operation utilizing hydrogen produced in the steam methane reactor, oxidation of feedstock is minimized and hydrogenation is maximized. Feedstock impurities are internally managed and a plurality of options for their removal is available. One of the more unique features enabled is the production of carbonate minerals through a modified Solvay process utilizing the metal chlorides produced via carbochlorination. (EP 0013586 B1, US 2013/0039824 A1) This along with internal reprocessing of carbon dioxide relieves or eliminates the need for dedicated carbon capture subsystems and their attributed energy losses.